The healthcare industry has been known to operate in a strong institutional environment (i.e. government regulations), and the implementation of inter‐organizational systems (IOS) has followed an institutional process. Extending this perspective across different tiers in the healthcare supply chain, we investigate how organizations in different tiers in the supply chain (i.e. hospitals, distributors and manufacturers) respond to institutional pressures when implementing IOS. How institutional dynamics unfold across multiple tiers of a supply chain is an uncharted area of research, and we take the theory‐building case study approach using data collected from ten organizations. Because organizations are embedded in their respective tiers, our within‐tier analyses are equivalent to cross‐organization analyses. In this regard, the cross‐case analyses occur at two different levels: at each tier level (i.e. across multiple hospitals, multiple distributors and multiple manufacturers) and across the supply chain (i.e. across all three tiers). The study shows how different institutional pressures such as coercive, mimetic, and normative manifest across the tiers. It also demonstrates how a differential mix of endogenous and institutional pressures lead to mixed organizational responses across the tiers. The propositions developed from the study enrich institutional theory arguments within the information systems and supply chain management disciplines. They highlight how the IOS implementation dynamics within and across different tiers in a supply chain result in heterogeneous rather than isomorphic consequences, thereby exposing the ‘iron cage’ of institutionalization.
